Coated and impregnated paper and process of manufacture thereof



Patented Sept. 19, 1939 coa'ran AND Mancunian Par-an annraocnss or MANUFACTURE rnaasor Nicholas E. Oglesby, 'lroy, N. Y.

No Drawing. Application July 6, 1986,

Serial No. 89.267

9 Claims. (CI. 91-68) The invention relates to the manufacture of paper and the treatment thereof and with regard to its more specific features to impregnated paper and paper which is coated or surfaced.

One object of the invention is to provide a flexible product. Another object of the invention is to provide a paper which has high wet strength.

Another object of the invention is to provide a paper particularly adaptablefor use as a flexible covering of high strength and ability to resist the action of water. Another object of the invention is to provide a flexible product which will not deteriorate rapidly with age.

1 Another object of the invention is to provide a paper particularly suitable for hanging and useful in the building trades. Another object of the invention is to provide a paper particularly suited for use as a covering for boxes, containers and the like. Another object of the invention is to pro- .vide a, paper particularly suitable for table covers and the like. Another object of the invention is to provide paper particularly applicable to manufacture into artificial leather and the like products. Another object 0: .;he invention is to provide a paper having some or all of the characteristics indicated and in condition to receive a coating, for example of abrasive grain. Another object of the invention is to provide a flexible base adaptable to receive a finishing coating or coatings applied toone or both sides and adapted to cooperate with one or both coatings, for example varnishes, resins and lacquers.

Another object of the invention is to provide a product for one or more of the uses set forth above which is water resistant. Another object of the invention is to provide a product for one or more of the uses set forth above which shall resist cracking. Another object of the invention is to provide a product of the character indicated in which the coating shall not readily peel oil the backing. Another object of the invention is to provide a process for the production of paper of the type indicated facilitating rapid production thereof. Another object of the invention is to provide a process of treating paper which plasticizes the paper. Another objectof the invention is to provide a process adapted to produce various degrees of flexibility in a paper product. Other objects of the invention are to provide a simple, inexpensive and safe process for the production of the products specified and which can be readily controlled in commercial use. Other objects will be in part obvious or in part pointed out'hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, and in theseveral steps and relation and order of each of said steps to one or more of the others thereof, all as will be illustratively described herein, and the scope of the application of which will be indicated'in the following claims. v

In carrying out the invention, I make use of any known machine for the production of paper from stock, as for example a Fourdrinier machine or a cylinder machine. I provide as a base paper stock any suitable furnish, for example rope, chemical wood pulp; purified wood pulp, jute, or 15 combinations thereof, and I may also use a certain amount of cotton or linen fiber. The stock may be disintegrated for the paper making machine in a beater with the beater roll lifted, in order to avoid hydration of the paper. I may then beat the stock to some extent, but preferably in order to introduce a maximum amount of materials hereinafter specified into the stock I avoid subsequent beating. The stock is then directed to the flow box of the Fourdrinier machine or the vats of a cylinder paper making machine and formed into paper. Subsequent to partial drying or after the paper has been completely dried, or after the roll of paper has been taken off the machine, I treat it with a 1% solution of viscose as cellulose 30 which has been pretreated with suflicient boric acid practically to neutralize the alkalinity of the viscose solution. The treatment of the paper with the solution of viscose may be effected by means of a tub sizer or the like. To the viscose 5 solution I may add ammonium carbonate in sufiicient quantities such that the liberation of carbon dioxide during a subsequent drying operation may tend .to complete the regeneration of the cellulose, such completion of regeneration being sub- 40 ject to control through the amount of ammonium carbonate added. In the type of product described, which is to be subsequently impregnated with an emulsion, it may sometimes be desired that this regeneration be incomplete-in the base 45 paper, since thereby a greater absorbency is accomplished. A subsequent heat treatment after the oil emulsion application completes the regeneration and develops a high degree of wet strength. If required, wetting agents such as 50 Mersall, "Nekal" or Magnus may be added to the viscose solution further to increase the absorbency ,of the finished paper. Mersall, "Nekal" and Magnus are each of them'neutralized sulphonated products of one or more of 55 oils, fats, higher alcohols and naphthalene derivatives.

In lieu of proceeding exactly as above specified, I may add the viscose in the beater,- but I prefer to add it thereafter as better results are usually obtained by adding the viscose to the paper after the paper web is formed.

Subsequent to the treatment with the viscose with or without the other ingredients, and according to any of the methods of application as hereinbefore specified, the paper is dried. Thereafter I treat the paper with a flexible oil or resin. I cause the paper to absorb an amount thereof which will leave in the dried paper, matter from about 50 to 150% of the original paper weight. The flexible oil or resin may be applied by means of a tub sizer or the like. The process, so far as the application of the viscose and the flexible oil or resin are concerned, may be continuous, if desired; that is to. say, tub sizers for each may be provided at diflerent positions along the drier. On the other hand, the flexible oil or resin may be applied after the paper is removed from the drier. The fatty oils are particularly useful in this invention. By the fatty oils I mean to include the semi-drying fatty oils such as for example soya bean oil, and the fatty drying oils such as China wood oil.

As a specific embodiment of the flexible oil or resin I may use the following formula:

Pounds Heavy blown soya bean oil 100 Oleic acid. 6. 6 Triethanolamine 3.5 Water 100 The triethanolamine should be added to the water and the olelc acid to the bean oil. The oil is then added slowly to the water while agitating with a high speed mixer, such as a Lightning or "Whirlwind mixer. The soya bean oil may be replaced with dejelled linseed oil or other suitable flexible oils. Likewise flexible resins may be used.

The mixture prepared as specified is a water emulsion of the oil or resin. The product is made more flexible by the use of water to wet and to swell the flbers. Preferably the water has a pH of 7.2 or more. The flbers, being wet with water, are not readily wetted by the oil, varnish or resin. In the drying process, while the fibers are still wet with water, the oil or resin is set to a flexible and a pliable but relatively immobile state, and the flbers being swollen and wet with water on their surfaces are not bound together to the extent that they would be if oils or resins, with or Pounds Heavy blown China-wood oil Oleic acid 3 Nopco B (sulphonated corn oil) 3 Sodium hydroxide .316 7 Water 100 In the case of either formula the oil-in-water emulsion is preferable to a water in oil emulsion,

but, a water in oil emulsion may in certain cases be used. 4

As an alternate method in which the paper flbers are swelled with water. .I may first saturate the paper with water containing oleic acid and triethanolamine in the proportion of 6.3 to 3.5, and in such concentration that the paper will take up 6 to 20% of the combined solids in the form of solution, and then apply hot oil to the paper while it is still wet. The paper should contain at least 18% and preferably more moisture at the time the oil is applied.

In either process, that is the emulsion process or the process in which the oil is applied to the wet sheet, the oil, varnish or resin used, as the case may be, should preferably be viscous and capable of being set to a relatively immobile state within a short time after heat is applied. A suitabl viscosity for the heavy blown soya bean oil used by way of illustration is from about 18 poises to about 40 poises at F. A suitable viscosity for the heavy blown China wood oil is from about 16 poises to about 47 poises at 77 F.

I have discovered that the most flexible results will be obtained where a semi-drying oil, such as soya bean oil or dejelled linseed oil, is used. By dejelled linseed oil I means an oil that has been produced by partially cracking a jelled linseed oil to destroy the flrm linseed oil jelly and produce instead thereof, a viscous definitely fluid product. Such dejelled linseed oil, soya bean oil, and similar semi-drying oils, when dried or set, tend to produce a very flexible and firm jelly, but under ordinary conditions of drying or curing do not set up to give a final product which is as hard or tough as China-wood oil similarly cured,

China wood oil being definitely in the class of drying oils. Where extremely flexible products are desired and the tensile strength of the impregnating medium is secondary, I prefer to use the semi-drying oils, such as soya bean oil or dejelled linseed oil heretofore described. If, however, a less flexible saturated product is desired in which the tensile strength of the impregnating medium is greater, I may use China-wood oil or ordinary linseed oil. However, by reason of the swelling of the flbers by water as specified, the

I product is, as compared with prior products, comparatively flexible.

I may produce degrees of flexibility intermediate between that produced with soya bean oil on the one hand and China-wood oil on the other hand by using an emulsion of mixed soya bean and China-wood oils. A suitable emulsion for this purpose maybe produced by replacing 25% of the soya bean oil shown in Example I by an equivalent weight of China-wood oil. In this case the product will be less flexible than that produced with soya bean oil, but more flexible than that produced with China-wood oil, and the permeating medium will have a tensile strength intermediate between the tensile strength produced by either oil. 4

In order to obtain specific properties for specific uses, I may use emulsions of various flexible varnishes and flexible resins, prepared with a variety of emulsifying agents, but I prefer to use in most cases for the emulsifying agent triethanolamineoleate since this material has to a high degree a softening or plasticizing effect on cellulose. As an alternative, however, I may use triethanolamine linoleate or triethanolamine palmitate, since these substances also are not only emulsifying agents but also have a definite plasticizing or softening effect upon paper and glycol, triethylene glycol or sorbitol.

similar ceilulosic bodies. As a plasticizing agent for the paper I may also add glycerine, diethylene Of these substances I prefer sorbitol as it is less subject to the influence of moisture, less volatile and more permanent.

With regard to the manner of application of the emulsions or any of them to the paper, I prefer a temperature of application of in the neighborhood of 90 F. This temperature will be varied somewhat with various emulsions and conditions of operation, and I note that the use of higher temperatures facilitates the ready saturation of the web with the emulsion but raising the temperature causes less stability of the emulsion.

The correct preparation of the base paper to be treated is important. The paper shouldhavehigh wet strength in order that it may withstand the treatments hereinbefore specified and this is more especially so in cases in which the oil or resin is applied after the paper is removed from the drier. In such acase the paper has to be put through a separate paper handling equipment and ought to be strong enough to withstand the treatment without breaking. The addition of the viscose solution is what gives this added wet strength according to the foregoing disclosure, but as an alternative I may use, instead of viscose, a solution of glue and glycerine to which I prefer to add paraformaldehyde to tan the glue. In this embodiment of the invention I may use 8 to 18% of 70 millipoise glue and 12 to 24% glycerine, percentages being of the weight of the paper, in tub sizing equipment or after the paper'is removed from the drier of the making machine.

Still another manner of achieving wet strength is to apply, as specified for glue and glycerine, glue and sorbitol in the same proportions. Sorbitol is preferred to glycerine in that the product is thereby less subject to changes in its properties with changes in moisture. Furthermore, sorbitol is less volatile and more permanent than glycerinel By way of comparing these alternatives for achieving wet strength I note that viscose, in the proportion specified, results in more flexibility to the paper, while tanned glue glycerine and tanned glue sorbitol, used as specified, result in higher wet strength. A particular advantage of the use of viscose lies in the fact that but a small percentage of solids are thereby incorporated into the paper; there are no added problems of chemical incompatibility in subsequent treatments, because the viscose used is regenerated to form cellulose which is chemically the same as or similar to base paper stock.

Instead of using paraformaldehyde to tan the glue I may use any other suitable agent, such as formaldehyde, which is preferably-added to the treated sheet as a 10 to 15% solution thereof in water, or on the other hand hexamethylene tetramine may be added to the glue solution or as a separate solution like the formaldehyde.

By my process as described in the various em-i bodiments thereof, it is possible to produce a saturated paper which is more pliable or flexible than the original base paper stock. I believe one important distinction to be this: I avoid the encasing of fibers of the paper with a layer of cured oil or resin. In processes which have been used to impregnate paper previously I believe that there has resulted an encasing of the fibers with cured oil or resin, usually while hot and dry and in a shrunken condition, with the result that subsequent absorption of moisture has caused a swelling of the fibers which then exerted a a force against the encasing layer. In such a condition the fibers have been less pliable than the original paper since they were too tightly bound together.

Furthermore, I believe that in the past the individual fibers have been bound together by the impregnating material, thereby definitely stiffening the product even though the bonding medium is itself flexible. I further believe that by wetting and swelling the fibers with water either simultaneously with or prior to the impregnation, I avoid both the rigid encasing and the excessive bonding together of the fibers. As confirmation of my theory I point to the fact that the present product is less dense than a product treated with oils without a swelling agent. Not only is water which I use a swelling agent but glycerine and sorbitol'are such also. Additional reasons why I am enabled to achieve the results as to flexibility specified reside in the fact that soyabean oil or dejelled linseed oil are more flexible than the paper fibers and -also in the fact that triethanolamine oleate has a softening action upon the paper fibers. The latter is true also of sorbitol, glycerine and triethylene glycol. These same materials also soften glue.

The paper stock for carrying out the invention. and the adjustment and type of paper making machine may be such as to produce a paper weighing 40 lbs. to the paper ream, in order satisfactorily to carry out the invention in any of the embodiments. However, higher or lower weights may be used according to the product desired.

Saturated paper prepared in accordance with I the present invention may be coated with various coating materials to produce products for many applications. Where the paper is to be used immediately for coating usually the curing of the oils or resins attained subsequent to the coating treatment will suflice to cause the curing of the impregnated oil or resin, thus avoiding spontaneous combustion. Otherwise, and especially where China-wood or linseed oils are employed, I further cure the impregnated paper with heat, for example in a drying room equipped for festooning the web, for example using a heat of from 130 to 175 F. for a period of approximately 8 to 24 hours.

The saturated paper may be used as a base for suitable coatings to produce a very satisfactory substitute for oilcloth, floor coverings and other useshereinbefore specified. Suitable coatings may consist of:

(a) Mixtures of blown linseed oil, pigments and thinners to which driers may or may not be added.

(b) Mixtures of lacquers and suitable pigments as, for instance, the nitrocellulose lacquers containing plasticizers, gums, pigments and volatile thinners in suitable proportions.

() Many varnishes compounded with pigments. The varnishes may be essentially rosin- China-wood oil varnishes or they may consist Avariety of coatings and methods of coating may be used. One advantage of my product for oilcloth and floor covering and other like uses is the wet strength treatment added during the.

T as a backing for flexible waterproof sandpaper,

but such is described and particularly claimed in my copending application Serial No. 89,268, flled July 6, 1936.

Coatings may be applied to the saturated paper prepared in accordance with this invention to produce many other useful articles, for example certain types of artificial leather may be prepared by coating my saturated paper.

In stating certain theories of the invention, it should be understood that such constitute the best explanation of the results achieved now known to me and the scope of the protection is not to be limited thereby.

It will thus be seen that there has been provided by this invention a method and an article in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As various possible embodiments might be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinbefore set forth is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A process of producing a coated article comprising selecting absorbent paper of suitable porosity, treating the paper with a water re-' sistant saturating medium which is flexible when set and selected from the group consisting of semi-drying oils, drying oils and resins in the presence of above substantially 18% of water, the percentage of water being figured on the base paper weight, to incorporate therein solids to the extent of from 50% to of the base paper weight, drying the saturated paper and applying to said saturated paper a flexible, water resistant finishing coating selected from the group consisting of paints, lacquers, varnishes and resins, whereby a durable waterproof composite article is formed which is not subject to cracking when bent and in which the bond between the finishing coat and the base is maintained when the article is subjected to flexing and bending in normal handling and use.

2. A process of producing a coated article comprising selecting absorbent paper of porosity such that from 50% to 150% of solids may be absorbed, saturating the paper with an aqueous emulsion of a water resistant medium which is flexible when set and selected from the group consisting of semi-drying oils, drying oils and resins to incorporate therein solids to the extent of from 50% to 150% of the base paper weight, drying the saturated paper and applying to said saturated paper a flexible, water resistant finishing coating selected from the group consisting of paints, lacquers, varnishes and resins, whereby a durable waterproof composite article is formed which is not subject to cracking when bent and in which the bond between the finishing coat and the base is maintained when the article is subjected to flexing and bending in normal handling and use.

3. A process of producing a coated article group consisting of paints, lacquers, varnishes,

and resins, whereby a durable waterproof composite article is formed which is not subject to cracking when bent and in which the bond between the finishing coat and the base is maintained when the article is subjected to flexing and bending in normal handling and use.

4. A process of producing a coated article comprising selecting absorbent paper of porosity such that from 50% to 150% of solids may be absorbed, including an agent adapted to add wet strength to the paper, saturating the paper with an aqueous emulsion of a water resistant medium which is flexible when set and selected from the group consisting of semi-drying oils, drying oils and resins to incorporate therein solids to the extent of from 50% to 150% of the base paper weight, drying the saturated paper and applying to said saturated paper a flexible, water resistant finishing coating selected from the group consisting of paints, lacquers, varnishes and resins, whereby a durable waterproof composite article is formed which is not subject to cracking when bent and in which the bond between the finishing coat and the base is maintained when the article is subjected to flexing and bending in normal handling and use.

5. A process of producing a coated article comprising selecting absorbent paper of porosity such that from 50% to 150% of solids may be absorbed, including an agent adapted to soften the paper, including an agent adapted to impart wet strength to the paper, saturating the paper with an aqueous emulsion of a water resistant medium which is flexible when set and selected from the group consisting of semi-drying oils, drying oils and resins to incorporate therein solids to the extent of from 50% to 150% of the base paper weight, drying the saturated paper and applying to said saturated paper a flexible, .water resistant finishing coating selected from the group consisting of paints, lacquers, varnishes and resins, whereby a durable waterproof composite article is formed which is not subject to cracking when bent and in which the bond between the finishing coat and the base is maintained when the article is subjected to flexing and bending in normal handling and use.

6. The product of claim 1 comprising porous base paper, said porous paper having its pores incompletely filled with a water resistant medium dried to a flexible condition, said water resistant medium being selected from the group consisting of semi-drying oils, drying oils and resins, said water resistant medium being present to the extent of 50% to 150% of the weight of the paper fibres, and a flexible water resistant finishing coating selected from the group consisting of paints, lacquers, varnishes and resins, said composite product being water resistant and not subject to cracking when bent and the bond between the finishing coat and the base being of a nature that will prevent splitting or II 9. Flexible coated paper according to claim 6 containing an agent adapted to soften the paper peeling when the composite article is subjected to flexing and bending in normal handling and use.

7. Flexible coated paper according to claim 6 containing an agent adapted to soften the paper. 8. Flexible coated paper according to claim 6 containing an agent adapted to add wet strength to the paper.

and an agent adapted to add wet strength to the paper. 

